Place the olive oil in an 8x8 glass baking dish. Place the chicken breasts in the dish, coating each side with oil. Squeeze the juice of 1/2 lemon over all. Slice the rest of the lemon and place a lemon slice on top of each chicken piece.

Bake in the preheated oven for 30 to 40 minutes until brown.

In a large skillet, melt the 1/4 cup butter or margarine. Add the sliced mushrooms. Sauté until the mushrooms are brown and have exuded their juices, about 6 minutes. Sprinkle with the flour and blend.

Add the chicken broth, stirring to make a medium thick sauce. Allow to reduce, adjusting with a little more broth to make a creamy sauce.

Add fresh parsley at the last minute. Spoon the sauce over the lemon baked chicken breasts. Serve immediately.